1. Technical Field of the Invention
The present invention relates to an apparatus for controlling automatic stop and restart of an engine. The apparatus performs idle stop control (hereinafter referred to as “IS control”) under which an engine (internal combustion engine), i.e. a drive source of travel, is stopped when predetermined conditions are met to perform idle stop.
2. Related Art
As disclosed in JP-A-2009-063001, an apparatus for controlling automatic stop and restart of an engine has been known, which can reduce fuel consumption. This apparatus performs idle stop when an engine stop allowance condition, that is, the fact that the brake pressure has exceeded a predetermined threshold, has been met. Thus, when a brake pressure has exceeded a predetermined threshold, the driver is determined as having an intention of stopping the vehicle, which is followed by performing IS control for the reduction of fuel consumption.
However, in the case where the engine is configured to stop under
IS control when the vehicle is decelerated as well, the engine may be stopped in a vehicle speed region in which the control using an anti-skid braking system (ABS) (hereinafter referred to as “ABS control” or “anti-skid control”) is performed. Therefore, when the fact that the brake pressure has exceeded a predetermined threshold is used as an engine stop allowance condition, the engine will be stopped in the state where the brake pressure exceeding the threshold is applied.
It has been confirmed that performing engine stop in the state where a brake pressure exceeding a threshold is applied may cause a problem that controllability of ABS control is deteriorated. For example, ABS control may be started according to the change of the friction coefficient of a road surface (hereinafter referred to as “road surface μ”). At the same time, an engine operation request may also be issued from the alternator or the compressor of an air conditioner, which are actuated by the engine. In other words, an engine restart request, which is not intended by the driver, may be issued at the same time. If the engine is restarted based on such an engine restart request, battery voltage may be lowered by the restart. In the event a high brake pressure has been applied when the battery voltage is lowered, pump load may become extremely large, affecting the operation of the motor for ABS control. As a result, controllability of ABS control will not be ensured any more.